E9C01

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase?

  1. A figure-8 oriented along the axis of the array

E9C02

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/4-wavelength apart and fed 90 degrees out of phase?

  1. A cardioid

E9C03

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed in phase?

  1. A Figure-8 broadside to the axis of the array

E9C04

Which of the following describes a basic rhombic antenna?

  1. Bidirectional; four-sided, each side one or more wavelengths long; open at the end opposite the transmission line connection

E9C05

What are the main advantages of a terminated rhombic antenna?

  1. Wide frequency range, high gain and high front-to-back ratio

E9C06

What are the disadvantages of a terminated rhombic antenna for the HF bands?

  1. The antenna requires a large physical area and 4 separate supports

E9C07

What is the effect of a terminating resistor on a rhombic antenna?

  1. It changes the radiation pattern from bidirectional to unidirectional

E9C08

What type of antenna pattern over real ground is shown in Figure E9-2?

  1. Elevation

E9C09

What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2?

  1. 7.5 degrees

E9C10

What is the front-to-back ratio of the radiation pattern shown in Figure E9-2?

  1. 28 dB

E9C11

How many elevation lobes appear in the forward direction of the antenna radiation pattern shown in Figure E9-2?

  1. 4

E9C12

How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus rocky ground?

  1. The low-angle radiation increases

E9C13

When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?

  1. It should be one or more wavelengths long

E9C14

How would the electric field be oriented for a Yagi with three elements mounted parallel to the ground?

  1. Horizontally

E9C15

What strongly affects the shape of the far-field, low-angle elevation pattern of a vertically polarized antenna?

  1. The conductivity and dielectric constant of the soil in the area of the antenna

E9C16

This question has been removed by the QPC

E9C17

What is the main effect of placing a vertical antenna over an imperfect ground?

  1. It reduces low-angle radiation

 

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